1. Field of the Invention
The present invention relates to a method of fixing a suspension to an actuator arm in a disk drive, and also to an actuator arm assembly manufactured by using the fixing method.
2. Description of the Related Art
In a recent magnetic disk drive as a kind of external storage device for a computer, size reduction and thickness reduction have proceeded, and low power consumption has also been desired. Further, to increase the storage capacity, an increase in recording density of a magnetic disk (hard disk) is required and the number of magnetic disks mounted in the disk drive is also increasing.
In a magnetic disk drive for a computer, a contact start and stop (CSS) system is generally adopted as the relation between a magnetic head and a magnetic disk. In this system, the magnetic head is kept flying a microscopic height from the magnetic disk during rotation of the disk owing to the balance between a flying force generated by air flow due to high-speed rotation of the disk and a pressing force of a suspension for pressing the head on the disk. When the rotation of the disk is stopped, the head is moved to a contactable zone on the disk and next comes into contact with the disk at the contactable zone. In the rest condition of the disk, the head is kept in contact with the disk.
The magnetic head is supported on the suspension at its front end. The suspension is fixed at its base end portion through a spacer to the front end of an actuator arm. That is, the base end portion of the suspension is spot-welded to the spacer, and the spacer is fixed by crimping to the front end of the actuator arm, thereby fixing the suspension to the front end of the actuator arm.
As a method of fixing the spacer to the front end of the actuator arm by crimping, it is known to pass a crimping ball through a cylindrical projection formed on the spacer to thereby expand the cylindrical projection, thus crimping the spacer to a hole of the actuator arm. In carrying out this crimping work, the spacer is pressed by a jig to prevent deformation of the spacer surface due to a crimping force. However, in such a conventional method of fixing the spacer by crimping, there is a tendency that the spacer is recessed on the upstream side (upper side) in the direction of passing of the crimping ball and is projected on the downstream side (lower side) in this direction.
As a result, twisting or warping of the spacer is apt to occur, causing an adverse effect on flying characteristics of the head. Such an uneven surface of the spacer causes variations in connecting force between the suspension and the actuator arm, which causes possible fluctuations in vibration characteristics of the suspension. Further, since the spacer is mass-produced by drawing, it is difficult to ensure the accuracy of the bore of the cylindrical projection through which the crimping ball is passed.